New research shows that a chemical compound found in many air fresheners, toilet
bowl cleaners, mothballs and other deodorizing products, may be harmful to the
lungs. Human population studies at the National Institute of Environmental Health
Sciences (NIEHS), a part of the National Institutes of Health, found that exposure
to a volatile organic compound (VOC), called 1,4 dichlorobenzene (1,4 DCB) may
cause modest reductions in lung function.

“Even a small reduction in lung function may indicate some harm to the lungs,” said
NIEHS researcher Stephanie London, M.D., lead investigator on the study. “The
best way to protect yourself, especially children who may have asthma or other
respiratory illnesses, is to reduce the use of products and materials that contain
these compounds.”

The researchers examined the relationship between blood concentrations of 11
common volatile organic compounds and lung function measures in a representative
sample of 953 adults. VOCs are a diverse set of compounds emitted as gases from
thousands of commonly used products, including tobacco smoke, pesticides, paints,
and cleaning products. VOCs are also released through automotive exhaust. The
researchers found that of the common VOCs analyzed, which included benzene, styrene,
toluene, and acetone, only the compound 1,4 DCB was associated with reduced pulmonary
function and this effect was seen even after careful adjustment for smoking,
The researchers found that 96 percent of the population samples had detectable
1,4 DCB blood concentration levels. African Americans had the highest exposure
levels and non-Hispanic whites the lowest.

This particular VOC, 1,4 DCB, is a white solid compound with a distinctive aroma,
similar to mothballs. It is typically used primarily as a space deodorant in
products such as room deodorizers, urinal and toilet bowl blocks, and as an insecticide
fumigant for moth control.

“Because people spend so much time indoors where these products are used, it’s
important that we understand the effects that even low levels might have on the
respiratory system,” said Leslie Elliott, Ph.D. a researcher on the NIEHS-funded
study. “There has been very little research on the health effects of this particular
compound in non-occupational settings.”

The researchers used data from the third National Health and Nutrition Examination
Survey (NHANES) and a special component of the study specifically designed to
assess the level of common pesticides and VOCs in the US population. NHANES III
is a nationally representative survey conducted by the Centers for Disease Control
and Prevention between 1988-1994 to determine the health and nutritional status
of the U.S. population.

Data from 953 adults 20-59 years old who had both VOC blood measures and pulmonary
function measures are included in the study published in the August issue of Environmental
Health Perspectives. Four pulmonary function measures were used in the analyses.
The researchers found modest reductions in pulmonary function with increasing
blood concentrations of 1,4 DCB.

There was approximately a 4 percent decrease in the test which measures forced
expiratory volume in 1(FEV1) second between the highest and lowest levels of
exposure. FEV1 is a commonly used index for assessing airway function and obstruction.

The researchers assessed the influence of other factors in an individual’s environment
that may be related to pulmonary function and to 1,4-DCB exposure, such as type
of heating, use of wood fires, age of house, presence of furred pets, occupation,
socioeconomic status, environmental tobacco smoke, smoking history, and diagnosis
of asthma or emphysema. The authors noted that participants might have been exposed
to other agents not assessed in this study1that have been linked to both respiratory
impairment and levels of 1,4-DCB.

“This research suggests that 1,4-DCB may exacerbate respiratory diseases,” said
David A. Schwartz, M.D., NIEHS Director. “As part of the new disease-focused
approach at NIEHS, researchers will use this information to better understand
the pathogenesis of respiratory diseases.” The NIEHS unveiled a new strategic
plan, "New Frontiers in Environmental Sciences and Human Health,” in
May aimed at challenging and energizing the scientific community to use environmental
health sciences to understand the causes of disease and to improve human health.
The plan can be accessed at http://www.niehs.nih.gov/external/plan2006.

Changes in FEV1 (with
95% confidence intervals) for each decile of 1,4-dichlorobenzene concentration
among participants in the NHANES III

The National Institute of Environmental Health Sciences (NIEHS), a component
of the National Institutes of Health, supports research to understand the effects
of the environment on human health. For more information on environmental health
topics, please visit our website at http://www.niehs.nih.gov/.

The National Institutes of Health (NIH) — The Nation's Medical Research
Agency — includes 27 Institutes and Centers and is a component of
the U.S. Department of Health and Human Services. It is the primary federal
agency for conducting and supporting basic, clinical and translational medical
research, and it investigates the causes, treatments, and cures for both common
and rare diseases. For more information about NIH and its programs, visit www.nih.gov.